Control apparatus



June 26, 1945; A, G. LARSON ET Al. 2,379,306

CONTROL APPARATUS Filed sept. 14, 1945 l D l? @RMR fl/f :ff' sfo@ P66shfff g; shiff Run Run snm ,I /L/ afm A TTORNE Y Patented June 26, 1945CONTROL APPARATUS Arthur G. Larson and Cecil S. Kelley, Forest Hills,Pa., assignors to The Westinghouse Air Brake Company, Wilmerding, Pa., acorporation of Pennsylvania Application September 14, 1943, Serial No.502,284

10 Claims.

This invention relates to control apparatus and more particularly tomeans for selectively controlling the positioning of a multi-positiondevice.

Reversible Diesel engines such as employed in marine service areprovided with a meneuvering gear operable to control differentoperations of the engines. Certain maneuvering gears have sevendifferent positions. There is a neutral or stop position for stoppingthe engine. At one side of stop position there is a shift position forpositioning the cams in the engine to provide for running of the enginein a direction which may be called forward, a start position forstarting the engine in said direction, and a run position to which thegear is moved and in which it is then carried after the engine isstarted. At the opposite side of stop position there is a shift positionfor positioning the enginecams to provide for reverse operation of theengine, a start position.

for starting the engine in reverse and a run position to which the gearis moved and in which it then remains after the engine is started inreverse.

One object of the invention is the provision of means including a fluidmotor controlled by the opposing pressures of springs and fluid underpressure for moving a device, suchas maneuvering gear above described,to any selected one of a plurality of different positions.

With the maneuvering gear in either of its run positions it would beundesirable to have same move back to stop position and stop the enginein case of failure of the actuating uid pressure in the motor.

Another object of the invention is therefore the provision of a fluidpressure motor operable in accordance with predetermined pressures offluid to selectively position a device such as a maneuvering gear and soconstructed as to provide for the maneuvering gear remainingin certainselected positions to which it may have been moved by fluid pressure incase of failure of such pressure.

Other objects and advantages will be apparent from the following moredetailed description of the invention:

In the accompanyingy drawing, the single figure is a diagrammatic View,partly in section and partly in outline, of a control apparatusembodying the invention.

Description control shaft of a reversible Diesel engine such as abovedescribed, and as indicated in the drawing by lines designated byappropriate legends, said shaft has a plurality of different positionsincluding a neutral or ,stop position and at a for- Ward side thereofshift, run and start positions and at the opposite or a reverse side ofstop position reversely arranged shift, run and start positions, the twostart positions being most remote from stop position, and the two shiftpositions immediately adjacent the stop position. Suitable detent meansnot shown in the drawing and not constituting a portion of the inventionare usually provided for holding the shaft I against unintended movementout of any one or more of the different positions such as the positionsindicated by the legends frun and stop The means controlled by the shaftI for accomplishing the starting, reversing, stopping, etc., of theengine are not shown in the drawing and will not be described since suchmeans are not pertinent to the invention or an understanding thereof.

The apparatus for controlling movement of shaft I to its differentpositions comprises a forward motor 2, an opposingly arranged reversemotor 3 and a manually operative control device 4.

The forward and reverse motors 2 and 3 comprise a common casing section5 arranged to be rigidly secured to the engine v(not shown) over theshaft I by any suitable securing means 6.

The casing section 5 has interiorly a boss 'I through which the shaft Iextends into said casing section. A lever 8 contained in the 'casingsection 5 is secured at its center to shaft I for rocking said shaft toits different positions. In the opposite ends of lever 8 are rollers 9and 9a journaled on pins IU and IIJa,'respectively.

The two rollers 9 and 9a are disposed over two parallel arrangedcylindrical portions I I and I2 of the casing section 5. Secured to thelower open ends of the portionsv II and I2 are the open ends of twocup-shaped cylinders I3 and I4, respectively, said portions andcylindersconstituting parts of the reverse and forward motors 3 and 2respectively, both of which are identical in structure and operation. i

` The reverse motor 3 further comprises a piston I5 contained incylinder I3 and cooperating with the closed end of said cylinder to forma pressure chamber I6 which is open to a control pipe I'I leading to thecontrol device 4. At 4the opposite side of piston I5 is a non-pressurechamber I8 open to the cylindrical portion II of the casing section 5.

The Piston I5 comprises a head I9, a combined stop and follower 2D and aexible packing cup 2I clamped between said head and follower by screws22 extending through said follower and having screw-threaded engagementwith said head. The head I9 is provided centrally with a hollowextension 23 projecting into the non-pressure chamber I8, and projectingfrom' said extensionI is a piston stem 24. The stem 24 is joined at an'annular shoulder 25 to a portion of reduced diameter and mounted overthis reduced portion, with one end engaging shoulder 25, is a sleeve 26the opposite end of which engages the roller 9. The sleeve 26 is securedto the stem 24 by screwthreaded engagement with the end of the reducedportion of said stem, and a set screw 21 carried by the sleeve is jammedagainst said reduced portion. Sleeve 26 is mounted to slide in a bearing28 supported in a shelf 29 in the casing section 5 adjacent roller 9.

The end of sleeve 26 engaging the shoulder 25 on the piston stem 24 isof greater diameter than said stem to provide an annular collar 30, butis of smaller diameter than the remainder off the sleeve for a chosendistance back from said end to provide a second but spaced annularcollar 3I. A spring cage 32 is slidably mounted on sleeve 26 and has atone end an inturned annular, collar 33 overlying collar 3l on saidsleeve. At the opposite end of cage 32 is an out-turned annular flange34 provided to engage the bearing 28 and to also support one end of thecoilspring 35 which encircles the cage.

The spring 35 is contained in a secondy spring cage 36, one end of whichis mounted to slide over the ilange 34 of cage 32, and said one end alsohas an out-turned annularflange 31 supporting one end of a coil spring38, the opposite end of which bears against the piston head I9. Theopposite end of spring cage 36 has an inturned annular flange 39 whichoverliesI the co1- lar 30 on one Vend of sleeve 26 and which alsosupports the opposite end of spring 35. I

With the, parts inthe condition shown in the drawing, it will be notedthat spring 38 is caged lbetween the piston head I9 and cage 36 which issupported at one end on collar 30 on sleeve 26, while spring 35 is cagedbetween the cage 36 and cage 32 which latter is connected tocollar 3| ofsleeve 26. Both springs are thus conned under a chosen degree ofpressure, and the force of spring 38 is greater than that of spring 35.

A spring cage 40 projecting into pressure cham-4 ber I6 is slidablymounted in an aperture provided centrally through the follower 2U and isprovided l within the piston head I9 with an annular outturned collar 4Iarranged to cooperate with said said follower to limit movementoutwardly of piston I9, but to provide for movement inwardly of saidpiston. A coil spring 42 under pressure supported at one end on thepiston head I9 within the hollow extension 23 thereof, extends into thecage 40 with its opposite end bearing against said cage and is providedto opposemovement of said cage into said piston head.

The forward motor 2 is structurally identical to the reverse motor 3 asabove mentioned and corresponding parts and chambers thereof havetherefore been indicated by the same reference numerals each bearing asufIiXu. In1 motor A2 the pressure chamber I6a, is connected to acontrol pipe 43 which leads to the manual control device 4, and theupper end of sleeve 26d engages roller 9a. f

A lever 5U may be connected to shafttl;

of the casing section 5 in any desired manner not shown in the drawing,for manual operation by an operator to rock said shaft to its differentposition.

The manual control device 4 which is provided for varying the pressureof fluid in pipes I1 and 43, may be of any suitable structure foraccomplishing this end, for example, it may be similar to a device fullydisclosed in the copending application of R. R, Stevens and Arthur G.Larson, Serial No. 494,612, led July 14, 1943, and assigned to theassignee of the present application.

Brieily, the manual control device 4 comprises a casing to which isconnected the two control pipes I'I and 43, and a pipe 44 through whichfluid under pressure from any suitable source may be supplied to thedevice. The device further comprises a control lever 45 having a neutralor stop position and at either thereof other positions indicated bylines and legends corresponding in name and relative disposition tothedifferent positions of the maneuvering gearNshaft-I.

In stop position of lever 45'the vcontrol `device 4 is operative toprovide uid at lequal degrees of pressure, such as 20v lbs., in .bothpipes I'I and 43. With the lever 45 at the "forward" side of stopposition the control device'is opera,- tive to open pipe I 'I toatmosphere andfto provide fluid in pipe 43 at pressures such as 35`lbs., 55 lbs., and 100 lbs. in the shiftf ,run'f and "start positions,respectively. At the .Sreversej side of "stop position like pressurewill be provided in pipe I'I in the corresponding lpositions while pipe43 will be open to atmosphere.

Operation With the lever 45 in stop position providing fluid at equaldegrees of pressure, suchfas 20 lbs., in both pipes I'I and 43, suchpressures effective in pressure chambers i6 and I6a on pistons I5 andI5a urge said pistons in an upwardly' `direction. This pressure of iiuidprovided on piston I5 in the reverse motor 3 is transmitted throughspring 38 and cage 36 to spring 35, the precompressed force of which,however, lexceeds lthe force developed by such pressure of fluidon'piston I5 so that said piston will move to but not beyond theposition shown in thedrawing. In a like manner piston I5a in the forward'motor 2 will be moved to but not beyond the position shown in thedrawing by the pressure of fluid provided in chamber I 6a with thecontrol lever` 45 in stop position. with the two pistons l5 and 5oj'thu's positioned, the sleeves 26 and 26a will engage the respectiverollers 9 and 9a with the lever B and maneuvering gear shaft I in thefstop position shown in the drawing. A

If the operator now desires to start the engine in a forward direction,he moves the control-lever 45 from stop position to shift positionat'the "forward side of stop position. In this shift" position pipe I'Iand thereby piston chamberl I6 are opened to the atmosphere whileuid'atfor instance 35 lbs. is provided in pipe 43 ad'thereby in chamberI6a below the piston I5a.

Since in the reverse motor 3 the springs 38 and 35 are at this timeconfined under pressure-between the piston `I5 and sleeve 26, therelease of fluid under pressure from chamber I6 willpermit these partsto freely move, except for frictional resistance, from the positionshown in the drawing in a downwardly direction until the spring cage 40engages the closed endof cylinder I3. In the forward motor 2 theincreaseA in pressure nphamber. I 6a on piston I5a.from.20.lbs.

to 35 lbs'. provides however a force which applied through spring 38a,and `cage 36a to spring 35a overcomes the force 'of the latter spring sothat the 'piston |50, is enabled to move in the direction of lever 8 andrelative to the spring cage 32a which is held against movement bycontact with the bearing 28a. The piston |50, will thus continue to moveunder the pressure of fluid in chamber I6a against the opposing force ofspring 35a until flange 39a on spring cage 35a contacts co1- lar 33a onthe spring cage 32 which prevents further movement of cage 32a, so thatthe force of spring 38a' then becomes effective to oppose furthermovement of piston Ia. The pressure of spring 38d exceeds the forcedeveloped by the 35 pounds "pressure of fluidA in chamber IIa on piston*I5a, so that Amovement of said piston will thereforeceaseat this time in'the position defined by Contact between flange 39a,l and collar 33a.This limited movement of piston I5a from the position shown in thedrawing rocks lever 8 in a counterclockwise direction and is such as torock shaft I from its stop position to the shift position at the forwardside of its stop position.

After the cams in the engine have been shifted incident to movement ofshaft I to forward shift position, then in order to start the engine theoperator moves lever 45 from the forward shift position to the forwardstart position and thereby provides in pipe 43 fluid at forexample 100lbs. pressure, while maintaining pipe I1 open to the atmosphere. Thishigher pressure effective in chamber Ilia on piston |50, provides aforce which exceeds the opposing force of spring 38a so that the pistonI5a then moves upwardly against the opposing force of spring 38a,r androcks the lever`8 and maneuvering control shaft I from forward shiftposition in the direction of the forwardstart position. When themaneuvering'gear shaft I attains the forward run position; spring cage40 associated with the reverse' piston'Vv I5 engages the closed end ofcylinder I3 so that the pressure of spring-42 will then oppose furthermovement of piston |5a. The pressure of fluid effective in chamber |6aon piston I 5a at this time is however sufficient to con.. tinuemovement of said piston against the opposing force of spring 38a, plusthat of spring 42 until follower 2|) associatedv with the piston I5engages the closed end of cylinder I3. In this position of the pistonsI5 and I5a,' the lever 8 and Athereby-the maneuveringgear control shaftI will be in their forward start position to provide for'starting of theengine in a forward direction. After the engine' is thus started, theoperator vmoves lever 45.back to forward run position for therebyreducing the pressure of fluid in pipe 43 to a degree such as 55 lbs.while still maintaining pipeA I1 open to the atmosphere. This reducedpressure acting in chamber Ilia on piston I5a produces a' force on saidpiston less than the opposing'forceof spring 38a plus that of spring 42,as a result of which piston I5a, is moved downwardly in its cylinder andthe piston I5 moves upwardly under the action of spring 42 until collar4I` on the end of spring cage 40 engages the follower 20 for renderingthe spring 42 ineffective.- The 55 lbs. pressure in chamber I6a actingon piston I5a exceeds however the force of spring 38a at this Atime so.that when the force of spring I42 is removed from piston I5 as justmentioned .the vtwo pistons will stop in the position in whichthespring'42 vis rendered ineffective. This move- ,ment of piston I5, byspring 42 as provided for by the reduction in pressure of fluid inchamber 'IGa on piston I5a rocks the control lever 8 and thereby themaneuvering gear shaftv I from its forward start position to itsadjacent run position in which position the parts will then remain aslong as it is desired that the engine continue' running in a forwardlydirection.

If the operator desires to stop the engine, he moves lever. 45 back toits stop position for thereby reducing the pressure of uid in pipe 43and pressure chamber IIa, to the 20 lbs. above mentioned and forproviding fluid at the same pressure in pipe I1 and piston chamber I6.The reduction in pressure in chamber IBa, on piston I5a renders thesprings 38a and 35a successively effective toreturn the piston |5a tothe stop" position shown in the drawing, while the pressure of fluidprovided in chamber I6 moves the piston I5 back to the position alsoshown in the drawing. This movement of piston I5 rocks the lever 8 andthereby the maneuvering control shaft I 'back to their stop position inwhich the opposite end of the lever will substantially contact sleeve26a of the forward motor 2.

If the operator now desires to start the vengine in the reversedirection, he moves lever 45 to the reverse shift position to providefluid at the 35 lbs. pressure in pipe I1 while opening pipe 43 to theatmosphere. This pressure of fluid in chamber I6 acting on piston I5provides a force which exceeds the opposing force of spring 35 asv lever8 and thereby the maneuvering control shaft I to the reverse shiftposition.

After the cams in the engine have been properly conditioned in responseto shafty I being moved to its reverse shift position, the operatormoves lever 45 to the reverse start position for providing iiuid at the100 lbs. pressure in pipe I1 while opening pipe 43 to the atmosphere.This higher pressure provided through pipe I1 on piston I5 then movessaid piston against spring 38 and rocks the lever 8 to move the pistonI5a to a position in which cage Mial contacts the closed end of cylinderI4, and then continues such movement against the opposing pressure ofspring 42a to the position in which the follower 20a engages the closedend of said cylinder. In this position of the two pistons 'the lever 8and the maneuvering gear shaft I will occupy the reverse start positionfor causing starting of the engine in the reverse direction.

After the engine is thus started in reverse, the operator moves thecontrol lever 45 from the reverse "start position to the adjacent runposition for thereby reducing the pressure uid in pipe I1 to the 55 lbs.above mentioned. This pressure on piston I5 develops a force exceedingthat of spring 38 but less than the combined forces of said spring andof spring 42a acting on piston I5a., as a result of which the latterspring moves the two pistons in opposite directions to positions inwhich spring 42a becomes ineffective and in which positions movement ofthe pistons will cease, and this movement of piston I5a turns the lever8 and maneuvering control shaft I from the reverse start position to theadjacent run position in which it will remain as long as it is desiredthat the engine operate in the reverse direction.

returns lever 45` to its stop position to thereby reduce'the pressure offluid in pipe I1 to the 20 lbsjab'ove mentioned and to at the same timesupply fluid through pipe 43 to piston chamber ,IBa at thesame pressure.'I'his reduction in pressure on piston I5 permits springs 38 and `35 toreturn said piston to the position shown in the drawing, while thepressure of fluid provided on piston I5a` returns same to the positionalso shown in the, drawing, and this movement of piston I5a moves lever8 and the maneuvering gear shaft I to stop position for stopping theengine.

l From the above description it will now be noted thatunder both theforward and reverse conditions of operation, one of the motors 2 or 3rocks the lever 8 and maneuvering gear shaft I in the direction awayfrom stop position but the other motor is required for rocking saidlever and shaft in the` opposite direction back toward and to stopposition. In` other words, the forward motor 2 can rock lever 8 andshaft I from "stop position to forward shift and start positions',butspring 42 in the reverse motor rocks said lever and shaft from theforward start position back to forward run position, while fluid.pressure `supplied through pipe I 'I to the reversemotor is required torock said lever and shaft from'- the latter position back to stopposition. Likewise, the reverse motor 3 can rock the lever 8 and shaft Ifrom st0p" position to the reverse shift and start positions, but returnto reverse run position to the stop position is desure of spring 42a onthe forward motor piston I5a whilereturn of said lever and shaft fromthe re verse run position to the stop positionis def pendent upon supplyof fluid under pressure to `acton the forward piston I5a.

s With this structure it will therefore be seen that there is no needfor any connection between the piston operated sleeves 26 and 26a andlever 8 other than mere contact with rollers 9 and 9a respectively,whereby said pistons and sleeves are both capable of movement away fromand relative to the lever 8 and shaft l. This is very important sincewith the lever 8 and shaft I in either run position a failure of fluidpressure on piston I5 or I 5a will merely result in movement of saidpiston under the action of spring 38 or 38a, respectively, relative toand away from lever 8 and will not therefore result in movement of lever8 out of either run position causing possibly an undesired stopping ofthe engine. Under such a condition, the engine can, however, be stoppedwhenever desired and also subsequently started and `reversed by manualoperation of lever 50, as will be apparent. f'

In case the pressure of fluid on piston I5 or ISa should fail with lever8 and-shaft I in either start position, said lever and shaft willautomatically be moved to the adjacent run position by the action ofeither spring 42a or 42 which then becomes ineffective, so that lever 8and shaft I will stop in the run position while piston I5 or I5a willcontinue movement relative to said lever back to the normal positionshown in the drawing. If the engine has already been started, thisautomatic return of lever 8 to the adjacent run position will thereforeallow the engine to run as intended in spite of the failure of fluidpressure.

In addition to the above, lever 50 also provides for manually moving themaneuvering gear shaft I to any selected position for starting, stoppingand reversing of the engine at a time when there' is no fluid pressureavailable in pipe 44. Upon each manual operation spring 42 will opposemanual movement of shaft I'from the ahead "run" position to theA aheadstart position, while spring 42awill oppose manual movement oi shaft .Itothe other start" position, but upon relief of manual force on lever50, said springs will automatically return the maneuvering gear shaft Itothe adjacent run position, thus avoiding rthe possibility of shaft Ibeing in a. start" position when not intended. The several springswillofl'er no resistance to manual adjustment of shafty I by lever 5I]between the two run positions.

As above described, movement of the lever l and shaft I from forward"frun position to stop'P position is accomplished by the provision of 20lbs. pressure in chamber I8 .or piston I8. which pressure however isinsufficient to move said4 piston against spring 35 to in turn movelever 8 and shaft I` past stop position, while to move said lever fromreversve" run position to stop position the same degree of pressure isprovided in chamber I8a to act on piston I5. It will therefore beapparent that in the former case where fluid pressure is supplied toactuate piston I5 it is not necessary to supply fluid under pressure toact on piston I5a since it will accomplish no purpose, and the same istrue in the latter case. However as above described, when fluid underpressure is supplied to actuate piston Il to move lever 8 and shaft Ifrom forward run" position to stop position the same pressure offiuidvis also provided on pistonl I5a, while when fluid under pressureis supplied to actuate the latter piston to turn lever 8 and shaft Ifrom reverse ,run position to fstop position the same pressure isprovided on piston I5. In other words, under these two dierentconditions the same degrees of pressureare provided on both pistons I5and I5a at the same time and this is desirable in that it permits theVuse of a single stop position forrthe operator's control lever 45 to`stop the engine when operating in either Ythe forward direction or inreverse direction; otherwise two stop positions for lever 45 would berequired.

Summary l Y It will now be seen that we have provided an apparatusembodying two oppositely arranged fluid pressure motors which areoperative to move s, member being controlled to any selected one of anumber of different positions as determined by different pressures offluid selectively provided fin either one or the other of said motors.Each of the motors comprises a piston controlled by the opposingpressure of fluid and of springs and the parts are so arranged that thefailure of fluid pressure on the controlling piston, vwith* consequentmovementA of said piston by its springs, will not move the member beingcontrolled from the position to which it had been previously moved. Themotor structure is relatively simple and compact in construction andpositive and accurate in operation in response to the differentpressures of fluid to which it may be subjected.

Having now described our invention, what we claim as new and desire tosecure by Letters Patent is: Y

l. In combination, a movable member having ya neutrallposition andanother position either side thereof, two independentlyoperative'fluid'preasure controlled motors oppositely connected to saidmember and selectively operable by fluid under pressure to move saidmember, respectively.

in either one direction or in the reverse direction to said neutral andother positions, each motor comprising a casing, a piston in said casinghaving positions corresponding to those of said member and having aone-way drive connection with said member for moving same when subjectto fluid under pressure, spring means arranged to oppose pressure ofactuating uid on said piston in neutral position thereof and uponmovement thereof by fluid under pressure past said neutral position tothe said other position at one `side of neutral position, means arrangedto render said spring means ineiective to oppose pressure of uid on saidpiston at the opposite side of neutral position, said member also havingat each side of neutral position a mid-position between said neutralposition and the said other position and said piston having a,corresponding mid-position, other spring means arranged to move saidpiston and thereby said member from said other position to therespective mid-position, and means limiting control action of said otherSpring means on said piston to between the two last named positions.

2. In combination, a movable member having a neutral position and ateither side thereof a plurality of positions including an extremeposition most remote from said neutral position, two fluid pressurecontrolled motor means opposedly connected to said member andselectively operable by fluid under pressure to move said memberrespectively in either one direction to said positions or in theopposite direction to said positions in the reverse order, each motorcomprising a casing, a piston in said casing having positionscorresponding to'said positions of said member and having a one-waydrive connection with said member for moving same in one direction whensubject to pressure of fluid and providing for movement away from andrelative to said member when not subject to fluid under pressure; springmeans, caging means connecting said spring means to said pistonrendering said spring means effective to oppose pressure of fluid onsaid piston in neutral position of said piston and upon movement of saidpiston out of neutral position by uid under pressure in the direction ofone of said eXtreme positions and ineffective upon movement out ofneutral position in the opposite direction, other spring meansassociated with said piston arranged to oppose movement of said pistonto the said eXtreme position thereof, and means arranged to render saidother spring means effective to control movement of said piston betweenthe last named eXtreme position and the position next adjacent said lastnamed extreme position and ineiective in all other positions.

3. In combination, a movable member having a neutral position and ateither side thereof a plurality of positions including an extremeposition most remote from said neutral position, two fluid pressurecontrolled motor means opposedly connected to said member andselectively operable by uid under pressure to move said memberrespectively in either one direction to said positions or in theopposite direction to said positions in the reverse order, each motorcomprising a casing, a piston in said casing having positionscorresponding to said positions of said member and having a one-waydrive connection with said member for moving same in one direction whensubject to pressure of fluid and providing for movement away from andrelative to said member when not subject to fluid under pressure; aplurality of springs associated with said piston, caging meansconnecting ysaid springs under pressure to said piston in such a manneras to render ment of said piston by fluid under pressure from v the lastnamed position to the respective extreme position and said caging meansbeing operative upon movement of said piston in the opposite directionto render said otherand one springs ineffective to oppose pressure ofiiuid on said piston in the said last named and neutral positions,respectively, of said piston, and other caging means operative to rendera third one of said springs effective to oppose movement of said pistonin the said opposite direction to and between the respective extremeposition and the next adjacent position andl ineiTective in all otherpositions.

' 4. In combination, a movable member having a neutral position and ateither side thereof a plurality of positions including an'extremeposition most remote from said neutral position, two uid pressurecontrolled motor means opposedly connected to said member andselectively operable by fluid under pressure to move said memberrespectively in either one direction to said positions Vor in theopposite direction to said positions in the reverse order, each motorcomprising a casing, a piston in' said casing having positionscorresponding to said positionsof said` member, a rod connected to oneside of said piston and arranged to engage said member for moving saidmember in one direction to successively its different positions whensaid piston is subject on .its opposite side to fluid pressure, said rodbeing capable of movement in the opposite direction with said piston,out' of engagement with and vrelative to said means rendering said otherand one springs successively ineffective in said another oneand neutralpositions, respectively, to oppose pressure of uid on said piston uponmovement of said piston in the opposite direction, another springassociated Vwith said piston operableto oppose movement thereof in saidopposite direction to ythe respective eXtreme position from an adjacentposition, and means arranged to render the last named spring ineffectiveinv said adjacent position to control movement of said piston uponmovement thereofv in said yone direction.

5. In combination, a movable member having a neutral position andk twoextreme positions, one at either side of saidneutral position, and twointermediate positions one between each extreme position and saidneutral position,- means for moving said member comprising alcasing, apiston in said casing operable by fluid under pressure to move saidmember in the direction of one of said extreme positions, a secondpiston in said casing movable by fluid under pressure to move `saidmember in the direction ofthe other extreme position, each of saidpistons vbeing capable of movement relative to said member upon areduction in pressure of uid, spring means cooperative with each pistonto oppose operation thereof to move said member from either intermediateposition to the adjacent extreme position and operable upon a reductionin pressure of fluid on the piston to move said member from the` lastnamed extreme position to the vadjacent intermediate position, otherspring means arranged to oppose operation of each piston by fluid underpressure to move said member from neutral position to the respectiveextreme position, and means cooperative with the last named spring meansto 'render same ineffective to oppose pressure of fluid on therespective abutment upon movement thereof in the opposite direction froma position inl which said member is in neutral position.

6. In combination, a movable member having a neutral position and twoextreme positions one at either side of neutral position and twointermediate positions one between each extremeposi- 8. In combination,a movable member having a neutral position, two fluid pressure motorsopposedly connected to said member, one for moving said member in onedirection and the other for moving same in the opposite direction, eachmotor comprising a casing, a piston in said casing having a connectionwith said member for moving said member in one direction and providingfor movement of said piston by said member and relative to said memberin the opposite direction, said piston being subject to variations inpressure of fluid in a pressure chamber in said tion and said neutralposition, means for moving said membercomprising a casing, two pistonsin said casing opposedly connected to said member, eachpiston beingoperative by a certain pressure of fluid to move said member to saidneutral position, by a greater pressureof uid to move said member to oneintermediate position, and by a still greater pressure of fluid tothe'adjacent extreme position, precompressed spring means acting on eachpiston'to define theposition thereof in which said member is in neutralposition when the piston is subject to said certainr pressure of fluid,other precompressed spring means associated with each piston tov definethe intermediate position -of said member to which it is moved by thelast named piston when subject to said greater pressure of fluid andyieldable to permitA movement of saidr memberto the'adjacent extremeposition by the vsaid last named pistonwhen subject to said stillgreater pressureof fluid, said other spring means being operative tomove said member from the extreme position back to the adjacentintermediate position upon a, reduction in the pressure of fluid on thesaid last named piston to said greater pressure, the connections betweensaid pistons and member providing for movement of either piston relativeto said member upon a reduction in pressure of fluid on the abutment.

'7. In combination, a movable member having a neutral position and threepositions at `either side of neutral position, means for moving saidmember comprising a casing, two pistons in said casing havingcorresponding positions and selectively operative by fluid underpressure to move said member either in one direction or in the oppositedirection to said positions and each piston being operable uponoperation by fluid pressure to move the other piston with said member, aplurality of spring means associated'with each .pistonl cooperative withdifferent pressures of fluid thereon to define said neutral positionandan adjacent position of saidmember and to oppose operation of thelast named pistonby fluid under pressure to move said member from thelast named position to the next adjacent or a third position, otheryspring means associated with each piston cooperative with pressure offluid thereon to define the said third position ofV said member and tooppose further movement of said member to the next or a fourth positionand operable upon a reduction in pressureof fluid on the last namedpiston to move said member back to said third position and beingthcn'ren'dered ineffective.

casing yand having a neutral position therein for contact with saidmember in its neutral position. spring means arranged to oppose movementof said `piston out of neutral position in the direction of `.saidmember 'upon an increase in fluid pressure onsaid piston, means arrangedto render said spring means ineffective to oppose movement of saidpiston upon movement thereof out of neutral position in the oppositedirection, stop means arranged to limit movement of said piston in saidopposite direction to define an extreme position of said member out ofneutral position, and other spring'means arranged'to oppose movement `ofsaid piston from a position of said member out of said extreme positioninto engagement with said stop means and for moving said piston out ofcontact with said stop means, and means arranged to render the lastnamed spring means ineffective upon movement of said piston to theposition in which saidlmember is in the position adjacent said extremeposition.

9. In combination, a movable member having a neutral position, two fluidpressure motors opposedly'connected to said member, one for moving saidmember in one direction and the other for moving same in the oppositedirection, each motor comprising a casing, a piston in said cas- 40 inghaving a connection with said member for moving said member in onedirection and providing for movement of said piston by said memberand'relative to said member, in the opposite direction, said pistonbeing subject to variations in pressure of fluid in a pressure chamberin said casing and having a neutral position therein for contact withsaid member in its neutral position, said piston in one motor beingmovable upon an increase in fluid pressure in said chamber from saidneutral position in a, direction to move said member from neutralposition and for moving said piston in the other motor from neutralposition in the opposite direction, each motor further comprising aplurality of caged springs arranged to become successively effective orineffective to oppose pressure of fluid on the respective piston indifferent positions thereof and of said member according to thepressures of such fluid, and another caged spring associated with eachpiston arranged to oppose movement thereof and of said member by thepiston of the other motor to an extreme position of said member, and toreturn said member from said extreme position to another positionadjacent said extreme position.

10. In combination, a member movable in 'either direction from a neutralposition, motor means comprising a casing, a piston in said casingoperable by fluid under pressure to move said member in one direction,another piston in said casing operable by fluid under pressure to movesaid member in the opposite direction, means providing a one-Way driveconnection between each piston and said member for rendering therespective' pistoncapable of movement relative to and out of drivingrelation with said member, spring means acting on each piston andoperable to oppose pressure of fluid on the respective piston in neutralposition of said member and upon movement of said member to one side ofneutral position by the respective piston, means confining said springmeans under pressure and operative to render same ineffective to opposepressure of fluid on the respective piston with said member at theopposite side of neutral position, and control means operable to provideon either piston uid at a pressure to move the piston against therespective spring means While at the same time subjecting the otherpiston to atmospheric pressure, said control means being also operableto provide on bothvpistons at the same time fluid at pressures in excessof atmospheric pressure but less than required to move the pistonsagainst the respective spring means.

ARTHUR G. LARSON. CECIL S. KELLEY.

